//
//  OnboardingView.swift
//  Nextcloud Cookbook iOS Client
//
//  Created by Vincent Meilinger on 15.09.23.
//

import Foundation
import SwiftUI

struct OnboardingView: View {
    @ObservedObject var userSettings: UserSettings
    @State var selectedTab: Int = 0
    
    var body: some View {
        TabView(selection: $selectedTab) {
            WelcomeTab().tag(0)
            LoginTab(userSettings: userSettings).tag(1)
        }
        .tabViewStyle(.page)
        .background(
            selectedTab == 1 ? Color("ncblue").ignoresSafeArea() : Color(uiColor: .systemBackground).ignoresSafeArea()
        )
        .animation(.easeInOut, value: selectedTab)
    }
}

struct WelcomeTab: View {
    var body: some View {
            VStack(alignment: .center) {
                Spacer()
                Image("CookBook")
                    .resizable()
                    .frame(width: 120, height: 120)
                    .clipShape(RoundedRectangle(cornerRadius: 10))
                Text("Tank you for downloading")
                    .font(.headline)
                Text("Nextcloud")
                    .font(.largeTitle)
                    .bold()
                Text("Cookbook")
                    .font(.largeTitle)
                    .bold()
                Spacer()
                Text("This application is an open source effort and still in development. If you encounter any problems, please report them on our GitHub page.\n\nCurrently, only app token login is supported. You can create an app token in the nextcloud security settings.")
                    .padding()
                Spacer()
            }
            .padding()
            .fontDesign(.rounded)
    }
}

struct LoginTab: View {
    @ObservedObject var userSettings: UserSettings
    
    enum LoginMethod {
        case v2, token
    }
    @State var selectedLoginMethod: LoginMethod = .v2
    @State var loginRequest: LoginV2Request? = nil
    
    enum Field {
        case server
        case username
        case token
    }
    @FocusState private var focusedField: Field?
    
    var body: some View {
        ScrollView(showsIndicators: false) {
            VStack(alignment: .leading) {
                HStack {
                    Spacer()
                    Image("nc-logo-white")
                        .resizable()
                        .aspectRatio(contentMode: .fit)
                        .frame(maxHeight: 150)
                        .padding()
                    Spacer()
                }
                Picker("Login Method", selection: $selectedLoginMethod) {
                    Text("Nextcloud Login").tag(LoginMethod.v2)
                    Text("App Token Login").tag(LoginMethod.token)
                }
                .pickerStyle(.segmented)
                .foregroundColor(.white)
                if selectedLoginMethod == .token {
                    LoginLabel(text: "Server address")
                    LoginTextField(example: "e.g.: example.com", text: $userSettings.serverAddress)
                        .focused($focusedField, equals: .server)
                        .textContentType(.URL)
                        .submitLabel(.next)
                        .padding(.bottom)
                    
                    LoginLabel(text: "User name")
                    LoginTextField(example: "username", text: $userSettings.username)
                        .focused($focusedField, equals: .username)
                        .textContentType(.username)
                        .submitLabel(.next)
                        .padding(.bottom)
                    
                    
                    LoginLabel(text: "App Token")
                    LoginTextField(example: "can be generated in security settings of your nextcloud", text: $userSettings.token)
                        .focused($focusedField, equals: .token)
                        .textContentType(.password)
                        .submitLabel(.join)
                    HStack{
                        Spacer()
                        Button {
                            userSettings.onboarding = false
                        } label: {
                            Text("Submit")
                                .foregroundColor(.white)
                                .font(.headline)
                                .padding()
                                .background(
                                    RoundedRectangle(cornerRadius: 10)
                                        .stroke(Color.white, lineWidth: 2)
                                        .foregroundColor(.clear)
                                )
                        }
                        .padding()
                        Spacer()
                    }
                }
                else if selectedLoginMethod == .v2 {
                    LoginLabel(text: "Server address")
                    LoginTextField(example: "e.g.: example.com", text: $userSettings.serverAddress)
                        .focused($focusedField, equals: .server)
                        .textContentType(.URL)
                        .submitLabel(.done)
                        .padding(.bottom)
                        .onSubmit {
                            if userSettings.serverAddress == "" { return }
                            Task {
                                await sendLoginV2Request()
                                if let loginRequest = loginRequest {
                                    await UIApplication.shared.open(URL(string: loginRequest.login)!)
                                }
                            }
                        }
                    Text("Submitting will open a web browser. Please follow the login instructions provided there.\nAfter a successfull login, return to this application and press 'Validate'.")
                        .font(.subheadline)
                        .padding(.bottom)
                        .tint(.white)
                    HStack{
                        Spacer()
                        
                        Button {
                            // fetch login v2 response
                            Task {
                                guard let res = await fetchLoginV2Response() else { return }
                                print("Login successfull for user \(res.loginName)!")
                                userSettings.username = res.loginName
                                userSettings.token = res.appPassword
                                userSettings.onboarding = false
                            }
                        } label: {
                            Text("Validate")
                                .foregroundColor(.white)
                                .font(.headline)
                                .padding()
                                .background(
                                    RoundedRectangle(cornerRadius: 10)
                                        .stroke(Color.white, lineWidth: 2)
                                        .foregroundColor(.clear)
                                )
                        }
                        .disabled(loginRequest == nil ? true : false)
                        .padding()
                        Spacer()
                    }
                }
                Spacer()
            }
            .onSubmit {
                switch focusedField {
                case .server:
                    focusedField = .username
                case .username:
                    focusedField = .token
                default:
                    print("Attempting to log in ...")
                }
            }
            .fontDesign(.rounded)
            .padding()
        }
    }
    
    func sendLoginV2Request() async {
        let hostPath = "https://\(userSettings.serverAddress)"
        let headerFields: [HeaderField] = [
            //HeaderField.ocsRequest(value: true),
            //HeaderField.accept(value: .JSON)
        ]
        let request = RequestWrapper.customRequest(
            method: .POST,
            path: .LOGINV2REQ,
            headerFields: headerFields
        )
        do {
            let (data, _): (Data?, Error?) = try await NetworkHandler.sendHTTPRequest(
                request,
                hostPath: hostPath,
                authString: nil
            )
            
            guard let data = data else { return }
            print("Data: \(data)")
            let loginReq: LoginV2Request? = JSONDecoder.safeDecode(data)
            self.loginRequest = loginReq
        } catch {
            print("Could not establish communication with the server.")
        }
        
    }
    
    func fetchLoginV2Response() async -> LoginV2Response? {
        guard let loginRequest = loginRequest else { return nil }
        let headerFields = [
            HeaderField.ocsRequest(value: true),
            HeaderField.accept(value: .JSON),
            HeaderField.contentType(value: .FORM)
        ]
        let request = RequestWrapper.customRequest(
            method: .POST,
            path: .NONE,
            headerFields: headerFields,
            body: "token=\(loginRequest.poll.token)".data(using: .utf8),
            authenticate: false
        )
        
        var (data, error): (Data?, Error?) = (nil, nil)
        do {
            (data, error) = try await NetworkHandler.sendHTTPRequest(
                request,
                hostPath: loginRequest.poll.endpoint,
                authString: nil
            )
        } catch {
            print("Error: ", error)
        }
        guard let data = data else { return nil }
        if let loginRes: LoginV2Response = JSONDecoder.safeDecode(data) {
            return loginRes
        }
        print("Could not decode.")
        return nil
    }
}

struct LoginLabel: View {
    let text: String
    var body: some View {
        Text(text)
            .foregroundColor(.white)
            .font(.headline)
            .padding(.vertical, 5)
    }
}

struct LoginTextField: View {
    var example: String
    @Binding var text: String
    
    var body: some View {
        TextField(example, text: $text)
            .textFieldStyle(.plain)
            .autocorrectionDisabled()
            .textInputAutocapitalization(.never)
            .foregroundColor(.white)
            .accentColor(.white)
            .padding()
            .background(
                RoundedRectangle(cornerRadius: 10)
                    .stroke(Color.white, lineWidth: 2)
                    .foregroundColor(.clear)
            )
    }
}